Firaxis, the creators of the saga Sid Meier's Civilization develop this video game of strategy and tactical action by turns based in the mythical saga X-COM. The aliens have invaded the Earth and to us touches us defend it costing us of an army of soldiers and scientists to which will train in our own base of operations. XCOM: Enemy Unknown Stands out by his wide options of personalización and the concept of permanent death, that will leave us without those troops that fall in the field of battle.